User Guide

Command Syntax
Siemens Building Technologies, Inc. 3-29
DC (Duty cycle)
Unitary pre-APOGEE APOGEE BACnet
  
Syntax
DC(pt1,pat1,...,pt8,pat8)
pt1
through
pt8
Name of the output points to be duty cycled.
• This parameter can be an LDO, LOOAL, LOOAP,
L2SL, or L2SP point type.
• Local, virtual, and physical points are valid for pt1,
pt2, pt3, and pt4.
pat1
through
pat8
Hourly pattern that describes how the point is duty cycled.
• This parameter can be a local, physical, or virtual
point, as well as an integer.
• This pattern is a four-digit code using the numbers 0
through 7.
• Each digit represents the on/off pattern for one 15-
minute segment of an hour. Table 3-1 lists the
numeric codes and their ON/OFF patterns.
Table 3-1. Duty Cycle Patterns and Numerical Codes.
Point Status During this Time
First 5
minutes
Second 5
minutes
Third 5
minutes
Code Number for
this 15-minute
On/Off Pattern
OFF OFF OFF 0
ON OFF OFF 1
OFF ON OFF 2
ON ON OFF 3
OFF OFF ON 4
ON OFF ON 5
OFF ON ON 6
ON ON ON 7
APOGEE PPCL User’s Manual
3-30 Siemens Building Technologies, Inc.
Use
Coordinates the operation of all available equipment to compensate
for additional equipment capacity that is not normally needed. During
normal system operation, some equipment is cycled off for short
periods of time to distribute equipment wear and reduce operating
costs.
A maximum of 8 points can be controlled with one DC command.
Do the following to create a duty cycle pattern:
1. Divide one-hour into four 15-minute segments.
2. Determine the ON/OFF state for each 5-minute increment of the
segment.
3. Using Table 3-1, assign a number to represent the ON/OFF
pattern for each 15-minute segment.
4. After the patterns are defined, enter the code numbers in reverse
order. The right-most digit defines the first 15-minute segment of
the hour. The left-most digit defines the last 15-minute segment
of the hour.
Example
1000 C THIS DC COMMAND DUTY CYCLES HFAN
1010 C ACCORDING TO THE FOLLOWING SCHEDULE:
1020 C
1030 C FIRST 15 MINUTES – ON, OFF, OFF (1)
1040 C SECOND 15 MINUTES – OFF, OFF, OFF (0)
1050 C THIRD 15 MINUTES – OFF, OFF, OFF (0)
1060 C FOURTH 15 MINUTES – ON, ON, ON (7)
1070 C
1100 DC(HFAN,7001)
Notes
The DC command has a priority of NONE. Therefore, the PPCL
program must be structured with IF/THEN/ELSE commands to
prevent conflicts between DC and other commands with the same
priority.
See also
DCR